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[Object] To provide a seat belt device which exhibits good smoothness
even at a low temperature of about -30.degree. C., which exhibits a small
reduction in smoothness even after repeated use for a long period of
time, or after use at a high temperature (80.degree. C.), and which has
good webbing retracting performance.
[Solution] A seat belt device includes a webbing 12 formed by applying a
webbing treatment agent to a webbing base material, a retractor 11 for
retracting the webbing 12, and an anchor member 13 through which the
webbing 12 is slidably hung. The webbing treatment agent is characterized
by containing as an essential component a hydrocarbon-based synthetic oil
with a viscosity of 35 to 100,000 mPas at -30.degree. C.

1. A seat belt device comprising: a webbing formed by applying a webbing
treatment agent to a webbing base material; a retractor for retracting
the webbing; and an anchor member through which the webbing is slidably
hung, wherein the webbing treatment agent is characterized by containing
as an essential component a hydrocarbon-based synthetic oil with a
viscosity of 35 to 100,000 mPas at -30.degree. C.

2. The seat belt device according to claim 1, characterized in that the
hydrocarbon-based synthetic oil comprises a poly-.alpha.-olefin
containing as an essential constitutional unit an .alpha.-olefin having 3
to 24 carbon atoms and/or an ethylene/.alpha.-olefin copolymer containing
as essential constitutional units ethylene and an .alpha.-olefin having 3
to 24 carbon atoms.

3. The seat belt device according to claim 1, characterized in that the
webbing treatment agent further contains a silicone oil with a viscosity
of 35 to 45,000 mPas at -30.degree. C., and the weight ratio of the
hydrocarbon-based synthetic oil/the silicone oil is 95/5 to 50/50.

4. The seat belt device according to claim 3, characterized in that the
silicone oil comprises at least one of polydimethylsiloxane and an
amino-modified silicone.

5. The seat belt device according to claim 1, characterized in that the
webbing treatment agent further contains a nonionic surfactant, and the
weight ratio of the hydrocarbon-based synthetic oil/the nonionic
surfactant is 99/1 to 30/70.

7. The seat belt device according to claim 1, characterized in that the
webbing base material is made of a 2/2 derivative twill woven fabric of
synthetic fibers.

8. The seat belt device according to claim 1, characterized in that the
webbing base material is made of a regular woven fabric or broken twill
woven fabric of synthetic fibers.

9. The seat belt device according to claim 1, characterized in that, when
a test is carried out at +20.degree. C. and -30.degree. C., in which the
webbing is hung over a horizontal test bar, which is described below, so
that both ends of the webbing are suspended vertically downward, an equal
load is applied to the both ends, then the load on one of the ends is
increased, and the amount of load W at which the webbing starts to move
is measured, W.sub.20/W.sub.-30 is 0.75 or more, where W.sub.20 is the
load W at +20.degree. C., and W.sub.-30 is the load W at -30.degree. C.

Description

TECHNICAL FIELD

[0001] The present invention relates to a seat belt device for restraining
an occupant in a rapidly moving vehicle, such as an automobile.

BACKGROUND ART

[0002] An automobile seat belt device has a structure such that a webbing
withdrawn from a retractor and hung through an anchor member can restrain
an occupant. As the anchor member, a member referred to as a shoulder
anchor, through anchor, through ring, or the like, which is fixed to a B
pillar or the like, is used in many cases.

[0003] PTL 1 describes that a small roller is provided on an anchor member
in order to facilitate withdrawal and retraction of the webbing. However,
an adequate effect is not necessarily obtained.

[0004] Furthermore, it has been a conventional practice to improve webbing
withdrawing and retracting performance by reducing friction between a
webbing and an anchor member. As the treatment agent therefor, there have
been proposed a coating treatment agent containing a blocked urethane
prepolymer compound (PTL 2), a polyether-polyester compound-based
treatment agent (for example, PTL 3), a treatment agent containing as a
major component a composition including a branched alcohol ester of a
higher fatty acid and a nonionic surfactant (PTL 4), and the like.

[0009] However, regarding the treatment agent of PTL 2, the resin falls
off after use of the seat belt for a long period of time, and the
smoothness and storability of the belt after use for a long period of
time tend to be degraded. Regarding the treatment agent of PTL 3, the
resin does not fall off, and smoothness and abrasion resistance at normal
temperature are at least satisfactory. However, smoothness cannot be
maintained in an extremely cold region where the winter temperature is
about -30.degree. C., which is a problem. Furthermore, the treatment
agent of PTL 4 is not satisfactory in terms of smoothness and abrasion
resistance.

[0010] It is an object of the present invention to solve the problems
associated with the conventional techniques and to provide a seat belt
device which exhibits good smoothness even at a low temperature of about
-30.degree. C., which exhibits a small reduction in smoothness even after
repeated use for a long period of time, or after use at a high
temperature (80.degree. C.), and which has good webbing retracting
performance.

Solution to Problem

[0011] According to a first embodiment, a seat belt device includes a
webbing formed by applying a webbing treatment agent to a webbing base
material, a retractor for retracting the webbing, and an anchor member
through which the webbing is slidably hung. The webbing treatment agent
is characterized by containing as an essential component a
hydrocarbon-based synthetic oil with a viscosity of 35 to 100,000 mPas at
-30.degree. C.

[0012] According to a second embodiment, a seat belt device according to
the first embodiment is characterized in that the hydrocarbon-based
synthetic oil comprises a poly-.alpha.-olefin containing as an essential
constitutional unit an .alpha.-olefin having 3 to 24 carbon atoms and/or
an ethylene/.alpha.-olefin copolymer containing as essential
constitutional units ethylene and an .alpha.-olefin having 3 to 24 carbon
atoms.

[0013] According to a third embodiment, a seat belt device according to
the first or second embodiment is characterized in that the webbing
treatment agent further contains a silicone oil with a viscosity of 35 to
45,000 mPas at -30.degree. C., and the weight ratio of the
hydrocarbon-based synthetic oil/the silicone oil is 95/5 to 50/50.

[0014] According to a fourth embodiment, a seat belt device according to
the third embodiment is characterized in that the silicone oil comprises
at least one of polydimethylsiloxane and an amino-modified silicone.

[0015] According to a fifth embodiment, a seat belt device according to
any one of the first to fourth embodiments is characterized in that the
webbing treatment agent further contains a nonionic surfactant, and the
weight ratio of the hydrocarbon-based synthetic oil/the nonionic
surfactant is 99/1 to 30/70.

[0016] According to a sixth embodiment, a seat belt device according to
the fifth embodiment is characterized in that the nonionic surfactant
comprises a polyhydric alcohol fatty acid ester and/or an alkylene oxide
adduct of a polyhydric alcohol fatty acid ester.

[0017] According to a seventh embodiment, a seat belt device according to
any one of the first to sixth embodiments is characterized in that the
webbing base material is made of a 2/2 derivative twill woven fabric of
synthetic fibers.

[0018] According to an eighth embodiment, a seat belt device according to
any one of the first to sixth embodiments is characterized in that the
webbing base material is made of a regular woven fabric or broken twill
woven fabric of synthetic fibers.

[0019] According to a ninth embodiment, a seat belt device according to
the first to eighth embodiments is characterized in that, when a test is
carried out at +20.degree. C. and -30.degree. C., in which the webbing is
hung over a horizontal test bar, which is described below, so that both
ends of the webbing are suspended vertically downward, an equal load is
applied to the both ends, then the load on one of the ends is increased,
and the amount of load W at which the webbing starts to move is measured,
W.sub.20/W.sub.-30 is 0.75 or more, where W.sub.20 is the load W at
+20.degree. C., and W.sub.-30 is the load W at -30.degree. C.

[0020] Test Bar

[0021] Diameter: 15 to 25 mm

[0022] Material: chromium-plated steel

[0023] Surface roughness: 7 to 17 .mu.m

Advantageous Effects of Invention

[0024] In the seat belt device of the present invention, even in an
extremely cold region at -30.degree. C., even after repeated use for a
long period of time, or even after use at a high temperature (80.degree.
C.), a retraction force close to that at normal temperature is propagated
to the front end portion of the webbing located in front of the anchor
member, and the webbing is retracted easily and quickly.

[0025] Since the seat belt webbing according to the present invention has
excellent smoothness, abrasion resistance, and heat resistance at normal
temperature and a low temperature (-30.degree. C.), excellent smoothness
is exhibited even in an extremely cold region where the winter
temperature is about -30.degree. C., and the storability of the seat belt
in the retracting device is not degraded even after repeated use for a
long period of time or even after use at high temperature. Thus, good
usability can be maintained.

[0026] Furthermore, in the webbing to which the webbing treatment agent
specified in any of the second to sixth embodiments is applied, the
reduction in smoothness is small even after use for a long period of
time, and good abrasion resistance is exhibited. In particular, in the
case where a webbing base material made of a 2/2 derivative twill woven
fabric is used, excellent advantageous effects can be obtained.

BRIEF DESCRIPTION OF DRAWINGS

[0027] FIG. 1 is a schematic view of a seat belt device.

[0028] FIG. 2 is a view illustrating a method of measuring a webbing
retracting force.

[0043] FIG. 1 is a perspective view of a seat belt device according to an
embodiment of the present invention. The seat belt device includes a
retractor 11, a webbing 12, the base end portion of which is retracted by
the retractor 11, a shoulder anchor 13 which is an anchor member and
through which the webbing 12 is hung, an anchor 14 for joining the front
end of the webbing 12 to the automobile body member, a tongue 15 through
which the front end portion of the webbing is passed, and the like.

[0044] In the present invention, as shown in FIG. 2, when a test is
carried out at +20.degree. C. and -30.degree. C., in which a webbing 12
is hung over a horizontal test bar 10 so that both ends 12a and 12b of
the webbing 12 are suspended vertically downward, an equal load (about
110 g assuming the spring retraction force) is applied to the ends 12a
and 12b, then the load on one of the ends (e.g., the end 12a) is
increased, and the amount of load W at which the webbing starts to move
is measured, W.sub.20/W.sub.-30 is 0.75 or more, preferably 0.75 to 0.95,
and particularly preferably 0.75 to 1.00, where W.sub.20 is the load W at
+20.degree. C., and W.sub.-30 is the load W at -30.degree. C. In
addition, the load W at +80.degree. C. is denoted by W.sub.80. The test
bar 10 is composed of a chromium-plated steel bar having a diameter of 15
to 25 mm and a surface roughness of 7 to 17 .mu.m.

[0045] In this seat belt device, since the sliding resistance between the
webbing 12 and the anchor 14 is small even at extremely low temperature,
the retracting force is propagated to the tongue side in the same manner
as that at normal temperature (20.degree. C.) even in an extremely cold
region, and thus the webbing retracting performance is satisfactory.

[0046] According to a preferred embodiment of the present invention, the
webbing is formed by applying a webbing treatment agent to a webbing base
material made of a woven fabric of polyester fibers.

[0047] Polyester yarns of 500 to 3,000 d (denier), in particular, about
1,000 to 1,500 d, are suitably used for the woven fabric.

[0048] The weave of the woven fabric is preferably a 2/2 derivative twill
weave shown in FIG. 4, but may be a regular weave shown in FIG. 3, a
broken twill weave shown in FIG. 5, or the like. The woven fabric weave
will be described with reference to FIGS. 6 to 9.

[0049] FIG. 6 is a schematic plan view showing a state in which warp yarns
and weft yarns are interlaced with each other in a regular weave. FIG. 7
is a view along arrow VII-VII in FIG. 6. FIG. 8 is a view along arrow
VIII-VIII in FIG. 6. FIG. 9 is a weave diagram of the fabric shown in
FIG. 6. In the regular twill weave, warp yarns 1 and 5 go over weft yarns
i and ii, go under weft yarns iii and vi, and go over weft yarns v and
vi. In such a manner, ups and downs are repeated.

[0050] The interlacing positions shift one by one from the warp yarn 1 to
the warp yarn 6.

[0051] In the present invention, in particular, in the case where a
webbing treatment agent, which will be described later, is applied, the
weave is preferably a 2/2 derivative twill weave. The reason for this is
that, as schematically shown in FIGS. 10 and 11, since the space between
warp yarns 100 in a 2/2 derivative twill weave shown in FIG. 11 is large
compared with a regular weave shown in FIG. 10, a webbing treatment agent
102 having a relatively low viscosity, which will be described later,
easily infiltrates into the weave. Furthermore, in the 2/2 derivative
twill weave, surface irregularities are larger than those of the regular
weave, and the contact area with an anchor member 101 is small, resulting
in low friction resistance.

[0052] A broken twill woven fabric is softer than a 2/2 derivative twill
woven fabric. Therefore, the 2/2 derivative twill weave having higher
rigidity than the broken twill weave is preferable as the webbing.

[0053] A webbing treatment agent suitable for being applied to the webbing
base material will be described in detail below.

[0054] The viscosity at -30.degree. C. of a hydrocarbon-based synthetic
oil (hereinafter, may be referred to as hydrocarbon-based synthetic oil
A), which is an essential component of the webbing treatment agent, is 35
to 100,000 mPas, preferably 100 to 50,000 mPas, more preferably 200 to
10,000 mPas, and particularly preferably 500 to 8,500 mPas. When the
viscosity at -30.degree. C. of the hydrocarbon-based synthetic oil A is
35 mPas or more, the oil film strength of the webbing treatment agent is
sufficient and the smoothness tends to be improved. When the viscosity at
-30.degree. C. is 100,000 mPas or less, friction does not increase
excessively, and smoothness and heat resistance at normal temperature and
low temperature are excellent. The method of measuring the viscosity at
-30.degree. C. is as follows.

[0056] Into a cylindrical test tube made of glass with an inner diameter
of about 22 mm and an overall length of about 115 mm, a measurement
sample is fed to a position 30 mm lower than the top. Temperature control
is performed for about 6 hours in a low-temperature thermostat bath "type
BFV-L" (manufactured by Yoshida Kagaku Co., Ltd.) set at -30.degree. C.,
and using a digital B-type viscometer "type DVL-B" (manufactured by Tokyo
Keiki Inc.), the value of the viscometer after one minute is read. The
Measurement was performed twice for the same sample, and the average
thereof is defined as the viscosity at -30.degree. C.

[0057] The hydrocarbon-based synthetic oil A may be a poly-.alpha.-olefin
containing as an essential constitutional unit an .alpha.-olefin having 3
to 24 carbon atoms, or an ethylene/.alpha.-olefin copolymer containing as
essential constitutional units ethylene and an .alpha.-olefin having 3 to
24 carbon atoms, although not limited thereto.

[0058] Specific examples of the .alpha.-olefin include propylene,
1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene,
1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene,
1-docosene, and 1-tetracosene. Among them, from the standpoint of
smoothness and heat resistance at low temperature, an .alpha.-olefin
having 6 to 18 carbon atoms is preferable, an .alpha.-olefin having 8 to
12 carbon atoms is more preferable, and 1-decene is particularly
preferable.

[0059] Furthermore, as the constitutional monomer of the
poly-.alpha.-olefin or the ethylene/.alpha.-olefin copolymer, one kind of
.alpha.-olefin may be used alone, or two or more kinds of .alpha.-olefin
may be used in combination.

[0060] Furthermore, the poly-.alpha.-olefin or the ethylene/.alpha.-olefin
copolymer may contain as a constitutional unit a monomer other than
ethylene and the .alpha.-olefin having 3 to 24 carbon atoms within the
range that does not influence the advantageous effects of the present
invention.

[0061] The method for producing the poly-.alpha.-olefin or the
ethylene/.alpha.-olefin copolymer is not particularly limited. The
poly-.alpha.-olefin or the ethylene/.alpha.-olefin copolymer can be
produced by ordinary methods (e.g., Japanese Unexamined Patent
Application Publication No. 1-163136 and Japanese Unexamined Patent
Application Publication No. 61-221207). For example, in a production
method, a catalyst (a radical catalyst, a metal oxide catalyst, a Ziegler
catalyst, a Ziegler-Natta catalyst, or the like) and a monomer (ethylene
and/or an .alpha.-olefin having 3 to 24 carbon atoms) are added to a
hydrocarbon-based solvent (butane, pentane, hexane, cyclopentane,
cyclohexane, xylene, toluene, or the like), polymerization is performed,
then, as necessary, the remaining catalyst is removed, the product is
subjected to fractional distillation, and hydrogenation is performed. The
polymerization temperature is usually -50.degree. C. to 150.degree. C.,
and preferably -10.degree. C. to 100.degree. C. The pressure during the
polymerization is usually 0.15 to 5 MPa. The polymerization time is
usually one minute to 20 hours. The present description hereby
incorporates by reference the entire contents of Japanese Unexamined
Patent Application Publication No. 1-163136 and Japanese Unexamined
Patent Application Publication No. 61-221207.

[0062] The webbing treatment agent may further contain a silicone oil
(hereinafter, may be referred to as silicone oil B).

[0063] The viscosity at -30.degree. C. of the silicone oil B is, from the
standpoint of smoothness, preferably 35 to 45,000 mPas, more preferably
50 to 20,000 mPas, particularly preferably 80 to 10,000 mPas, and most
preferably 150 to 8,000 mPas.

[0064] The weight ratio A/B of the hydrocarbon-based synthetic oil A to
the silicone oil B is preferably 95/5 to 50/50, more preferably 90/10 to
60/40, and particularly preferably 85/15 to 70/30.

[0065] In other words, the content of the silicone oil B is preferably 5%
to 50% by weight, more preferably 10% to 40% by weight, and particularly
preferably 15% to 30% by weight, relative to the total weight of the
hydrocarbon-based synthetic oil A and the silicone oil B. When the
content of the silicone oil B is 5% by weight or more, smoothness at low
temperature is satisfactory. When the content of the silicone oil B is
50% by weight or less, abrasion resistance is satisfactory.

[0066] Examples of the silicone oil B include polydimethylsiloxane,
polymethylphenylsiloxane, an amino-modified silicone, a
polyether-modified silicone, a carboxy-modified silicone, an
alkyl-modified silicone, and a polyester-modified silicone. Among them,
from the standpoint of smoothness at low temperature and high
temperature, polydimethylsiloxane and an amino-modified silicone are
preferable, and polydimethylsiloxane is more preferable.

[0068] The webbing treatment agent may further contain a nonionic
surfactant (hereinafter, may be referred to as nonionic surfactant C).

[0069] Examples of the nonionic surfactant C include a polyhydric alcohol
fatty acid ester, an alkylene oxide adduct of a polyhydric alcohol fatty
acid ester (hereinafter, alkylene oxide is abbreviated as AO), an AO
adduct of an aliphatic alcohol, a fatty acid alkanolamide, a
polyoxyalkylenealkylphenyl ether, a polyoxyalkylene alkyl amine, and an
alkyl amine oxide. Among them, from the standpoint of emulsifiability of
the hydrocarbon-based synthetic oil A and the silicone oil B, a
polyhydric alcohol fatty acid ester, an AO adduct of a polyhydric alcohol
fatty acid ester, an AO adduct of an aliphatic alcohol, and a
polyoxyalkylenealkylphenyl ether are preferable, and a polyhydric alcohol
fatty acid ester and an AO adduct of a polyhydric alcohol fatty acid
ester are more preferable.

[0070] Examples of the AO include ethylene oxide (hereinafter, may be
abbreviated as EO), propylene oxide (hereinafter, may be abbreviated as
PO), and butylene oxide. One kind of AO may be used or two or more kinds
of AO may be used in combination. In the case where two or more kinds of
AO are used in combination, either block addition (chip type, balance
type, active secondary type, or the like) or random addition may be
employed.

[0072] Specific examples of the AO adduct of a polyhydric alcohol fatty
acid ester include an ethylene oxide-propylene oxide random adduct of
trimethylolpropane monostearate, an ethylene oxide adduct of sorbitan
monolaurate, an ethylene oxide adduct of sorbitan monostearate, an
ethylene oxide adduct of sorbitan distearate, and an ethylene
oxide-propylene oxide random adduct of sorbitan dilaurate. The number of
moles of added AO is preferably 1 to 60 moles, and more preferably 10 to
50 moles.

[0073] The weight ratio A/C of the hydrocarbon-based synthetic oil A to
the nonionic surfactant C is, from the standpoint of emulsifiability,
preferably 99/1 to 30/70, more preferably 80/20 to 35/65, and
particularly preferably 60/40 to 40/60.

[0074] The webbing treatment agent may contain a component D other than
the hydrocarbon-based synthetic oil A, the silicone oil B, and the
nonionic surfactant C within the range that does not hinder the
performance. Examples of the component D include a lubricating agent, an
antistatic agent, an antioxidant, an ultraviolet absorber, and a pH
adjuster.

[0075] Examples of the lubricating agent include an ester compound
composed of an aliphatic (monohydric or polyhydric) alcohol and a
monobasic acid (2-ethylhexyl stearate, trimethylolpropane trilaurate, or
the like), a polyether polyester compound composed of a polyalkylene
glycol, a monobasic acid, and a dibasic acid, and animal and vegetable
oil (beef tallow, coconut oil, castor oil, or the like).

[0077] Examples of the antioxidant include hindered phenol antioxidants
{triethylene
glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], and the
like}, and amine antioxidants
[2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-tert-butylanilino)-1,3,5-triaz-
ine, and the like].

[0078] Examples of the ultraviolet absorber include benzotriazole-based
ultraviolet absorbers [2-(3,5-di-tert-amyl-2-hydroxyphenyl)benzotriazole,
and the like], and hindered amine ultraviolet absorbers
[bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, and the like].

[0079] Examples of the pH adjuster include lower fatty acids (acetic acid,
lactic acid, and the like), ammonia, and hydroxides of alkali metal
(sodium hydroxide, potassium hydroxide, and the like).

[0080] The content of the component D is usually 0% to 30% by weight,
preferably 0% to 20% by weight, and more preferably 0% to 15% by weight,
based on 100% by weight of the solid content of the treatment agent. In
the present invention, the term "solid content" refers to the content of
components other than an aqueous medium, which will be described later.

[0081] The component D may be incorporated into the treatment agent as
described above. Alternatively, as will be described later, in the
treatment process, two or more baths may be prepared, and after treatment
with the treatment agent containing the hydrocarbon-based synthetic oil
A, retreatment may be performed in the bath containing the other
component D.

[0082] The form of the webbing treatment agent may be either the treatment
agent itself containing the hydrocarbon-based synthetic oil A, etc., or
an aqueous dispersion further containing an aqueous medium. From the
standpoint of workability, an aqueous dispersion is preferable.

[0083] In the case of an aqueous dispersion, as the aqueous medium, water,
a hydrophilic organic medium, or a mixed medium of these may be used.
Examples of the hydrophilic organic medium include alcohols (methanol,
ethanol, isopropanol, and the like), ketones (acetone, methyl ethyl
ketone, and the like), and carboxylate esters (ethyl acetate, and the
like). In the case of a mixed medium, the percentage of water is
preferably 80% by weight or more.

[0084] In the case where the treatment agent is composed of the
hydrocarbon-based synthetic oil A, the silicone oil B, the nonionic
surfactant C, and the other component D, for example, a production method
is used in which the hydrocarbon-based synthetic oil A, the silicone oil
B, the nonionic surfactant C, and the other component D are fed into a
mixing tank equipped with a stirrer, and stirring is performed until
achieving homogeneity.

[0085] In the case where the treatment agent is in the form of an aqueous
dispersion containing the hydrocarbon-based synthetic oil A, the silicone
oil B, the nonionic surfactant C, and the other component D, examples of
the production method include the followings:

i) A method in which a mixture of A, B, C, and D is produced, and the
mixture is dispersed in an aqueous medium. ii) A method in which a
mixture of A, C, and D and a mixture of B, C, and D are produced, and the
two mixtures are dispersed in the same aqueous medium. iii) A method in
which, in the method ii) described above, the two mixtures are dispersed
in different aqueous media to produce two aqueous dispersions, and then
these are mixed together. iv) A method in which a mixture of A, B, and D
is produced, the mixture is dispersed in an aqueous medium to obtain an
aqueous dispersion, and then C is added and dispersed therein. v) A
method in which a mixture of A, C, and D is produced, the mixture is
dispersed in an aqueous medium to obtain an aqueous dispersion, and then
B is added and dispersed therein.

[0086] In the production methods i) to v), the technique of emulsifying
the aqueous dispersion is not particularly limited, but examples thereof
include spontaneous emulsification, phase reversal emulsification,
mechanically forced emulsification, high-pressure emulsification, a paste
process, and simultaneous emulsification. Among them, from the standpoint
of ease of production, spontaneous emulsification, phase reversal
emulsification, and mechanically forced emulsification are preferable.

[0087] As a method of applying the webbing treatment agent to the webbing,
for example, a method is suitable in which a seat belt webbing after
having been dyed is treated by a padding process in a treating bath
filled with a treatment agent in the form of an aqueous dispersion,
although the method is not limited thereto. The concentration of the
solid content in the treating bath is preferably 0.05% to 20% by weight,
more preferably 0.1% to 10% by weight, and particularly preferably 0.5%
to 8% by weight. After the seat belt webbing is treated with the webbing
treatment agent, preferably, the seat belt webbing is subjected to a step
of drying at 40.degree. C. to 220.degree. C., and more preferably, the
seat belt webbing is dried at 80.degree. C. to 170.degree. C.

[0088] The amount of application of the treatment agent to the seat belt
webbing treated with the treatment agent described above is not
particularly limited, but is preferably 0.01% to 3% by weight, more
preferably 0.05% to 2% by weight, and particularly preferably 0.1% to
1.5% by weight, relative to the weight of the seat belt webbing.

EXAMPLES

[0089] The present invention will be further described below with
reference to examples. However, it is to be understood that the present
invention is not limited thereto. Unless otherwise specified, "%" means
"% by weight", and "part" means "part by weight".

[0090] The hydrocarbon-based synthetic oil A, the silicone oil B, the
nonionic surfactant C, and the polyether-polyester compound used in
Examples and Comparative Examples are as follows:

[0091] A webbing base fabric (dyed black) made of a 2/2 derivative twill
weave of polyester yarns of 1,500 d, with a width of 47 mm and a
thickness of 1.15 mm, was prepared. A webbing treatment agent having the
composition shown in Table 1 was gradually added under stirring into
water to thereby prepare an aqueous dispersion liquid (liquid containing
a webbing treatment agent) with an effective component concentration of
2%. The webbing base fabric was subjected to immersion treatment in the
aqueous dispersion liquid using a padding process, and then squeezed by a
mangle at a squeeze rate of 50%. Next, drying was performed at
150.degree. C. for 3 minutes, and thereby a treated webbing to which the
treatment agent had been applied in an amount of 1% on the basis of solid
content was produced.

[0092] The resulting webbing was fitted to a seat belt retractor and hung
over an anchoring member as shown in FIG. 2, and a tongue was installed
on the front end thereof.

[0093] Regarding the webbing, W.sub.80, W.sub.20, and W.sub.-30 were
measured in accordance with the method shown in FIG. 2, and
W.sub.20/W.sub.-30 and W.sub.20/W.sub.80 were calculated. The results
thereof are as shown in Table 1. The load initially applied to both ends
was 110 g.

Examples 2 to 15

[0094] W.sub.20/W.sub.-30 and W.sub.20/W.sub.80 were calculated in the
same manner except that the webbing treatment agents for Examples 2 to 15
shown in Tables 1 to 3 were used. The results thereof are as shown in
Table 1.

Examples 16 to 27 in which Webbing of Regular Weave was Used

[0095] W.sub.20/W.sub.-30 and W.sub.20/W.sub.80 were calculated in the
same manner except that a regular woven fabric was used as the webbing
base fabric in each of Examples 1 to 9 and 12 to 14. The results thereof
are also shown in Tables 1 to 3.

Comparative Examples 1 to 3

[0096] W.sub.20/W.sub.-30 and W.sub.20/W.sub.80 were calculated as in
Example 1 except that the webbing treatment agents for Comparative
Examples 1 to 3 shown in Table 1 were used. The results thereof are as
shown in Table 4.

Comparative Examples 4 and 5

[0097] The webbing treatment agents for Comparative Examples 2 and 3 shown
in Table 4 were applied to webbing base fabrics of regular weave in the
same manner to produce treated webbings, and W.sub.20/W.sub.-30 and
W.sub.20/W.sub.80 were determined. The results thereof are shown in Table
4.

Production Example 1

Synthesis of Polyether-Polyester Compound

[0098] 45 Parts of 1,4-butanediol and 369 parts of tetrahydrofuran
(hereinafter abbreviated as THF) were placed in a pressure-tight reaction
container equipped with a stirrer and a thermometer, 5 parts of boron
trifluoride tetrahydrofuran complex as a catalyst was added thereto, and
the container was nitrogen purged and hermetically sealed. 82.5 Parts of
EO was added dropwise thereto at 40.degree. C. over 2 hours to obtain 496
parts of a diol component, i.e., a random copolymer. Subsequently, 300
parts of the resulting diol component, 30.7 parts of adipic acid as a
dibasic acid, and 168 parts of oleic acid as a monobasic acid were placed
in a reaction container equipped with a stirrer, a thermometer, and a
nitrogen-introducing tube, and 1.5 parts of para-toluenesulfonic acid as
a catalyst was added thereto. Under nitrogen stream, reaction was
performed at 150.degree. C. for 12 hours to thereby obtain a
polyether-polyester compound.

[0099] W.sub.20/W.sub.-30 and W.sub.20/W.sub.80 were evaluated on the
basis of the evaluation criteria described below, and the evaluation
results are shown in Tables 1 to 4.

[0100] Regarding the seat belt webbings treated with the treatment agents
in Examples 1 to 27 and Comparative Examples 1 to 5, abrasion resistance
was measured by the method described below.

[0101] <Evaluation Method of Abrasion Resistance>

[0102] A treated seat belt webbing (length: 1.5 m) is moved reciprocally
over a hexagonal bar (according to JIS G 4604) serving as an abrasive,
2,500 times, under a load of 500 g, to wear the surface of the webbing.
The tensile strength was measured before and after abrasion by the method
described in JIS-G4604, and the strength retention rate (%) after
abrasion was calculated. The larger value indicates better durability
after use for a long period of time and higher abrasion resistance.
Furthermore, from the strength retention rate (%) after abrasion,
abrasion resistance was evaluated on the basis of the criteria described
below. The results are shown in Tables 3 and 4.

[Evaluation Criteria]

TABLE-US-00007
[0103] Strength retention rate after abrasion of 94% or more Excellent
Strength retention rate after abrasion of 91% or more and less Good
than 94%
Strength retention rate after abrasion of 88% or more and less Average
than 91%
Strength retention rate after abrasion of 85% or more and less Passing
than 88%
Strength retention rate after abrasion of less than 85% Failure

[0104] As is evident from Examples and Comparative Examples described
above, the seat belt devices of the present invention have good webbing
retracting performance even in an extremely cold region, and among them,
Examples 1 to 4 and 7 and 8 in which the webbing base fabric is made of a
2/2 derivative twill weave have particularly good webbing retracting
performance. In particular, in Examples 1 and 7, the composition of the
treatment agent is suitable, the coefficient of friction is low as shown
in the friction test described below, and the webbing made of the 2/2
derivative twill weave to which the treatment agent is easily applied is
used. Therefore, the best results are obtained.

[0105] Furthermore, as is evident from Tables 3 and 4, the seat belt
webbings of the present invention excel in smoothness, abrasion
resistance, and heat resistance at normal temperature and a low
temperature (-30.degree. C.)

[0106] [Reference Evaluation Test]

[0107] The friction resistance of a 2/2 derivative twill weave webbing
used in Example 1 and a regular weave webbing (before attaching the
agent) was measured in accordance with JIS K 7125 (1999), using a weight
of 200 g or 500 g. Note that JIS K 7125 (1999) corresponds to ASTM 1894.

[0108] The test table in the friction test is a chromium-plated steel
plate. The measurement results of the coefficient of static friction and
the coefficient of dynamic friction are shown in Table 5 and FIGS. 12 to
15. As shown in Table 5, the 2/2 derivative twill weave has lower values
in the coefficient of static friction and the coefficient of dynamic
friction than the regular weave.